sql語句學(xué)習(xí)(已修改)
2025-08-16 09:47 本頁面
【正文】 SQL語句學(xué)習(xí) 整理人：金兆燦第一章 查詢語句 簡單的查詢： 3 操作符和通配符 3 4SELECT AVG(vote) ‘the_average’ FROM opinion 4 4SELECT COUNT(au_lname) FROM authors 4SELECT COUNT(au_lname) FROM authors WHERE au_lname=’Ringer’ 4SELECT COUNT(DISTINCT au_lname) FROM authors 4SELECT COUNT(*) FROM authors 4SELECT COUNT(vote) FROM opinion_table WHERE vote=1 5 5SELECT AVG(vote) FROM opinion 5 5SELECT SUM(purchase_amount) FROM orders 5 5SELECT MAX(vote) FROM opinion 5SELECT MIN(vote) FROM opinion 函數(shù)、過程 5通過匹配一定范圍的值來取出數(shù)據(jù) 6SELECT username FROM opinion WHERE vote6 and vote11 6SELECT username FROM opinion WHERE vote BETWEEN 7 AND 10 6SELECT username FROM opinion WHERE vote=1 or vote 6SELECT username FROM opinion WHERE vote IN (1,10) 6SELECT vote FROM opinion WHERE username IN (‘Bill Gates’,’President Clinton’) 6SELECT username FROM opinion WHERE vote NOT BETWEEN 7 and 10 6SELECT vote FROM opinion 6 6SELECT CONVERT(CHAR(8),price)+’US Dollars’ FROM orders 6SELECT ‘The vote is’+CONVERT(CHAR(1),vote) FROM opinion 7The vote is 1 7 7 7SELECT site_name FROM site_directory WHERE site_desc=’trading card’ 7SELECT SITE_name FROM site_directory WHERE site_desc LIKE ‘%trading cark%’ 7SELECT site_name FROM site_directory WHERE site_name LIKE ‘[AM]%’ 7SELECT site_name FROM site_directory WHERE site_name LIKE ‘[NZ]%’ 7SELECT site_name FROM site_directory WHERE site_name LIKE ‘[ABC]%’ 8SELECT site_name FROM site_directory WHERE site_name LIKE ‘[CFY]%’ 8SELECT site_name FROM site_directory WHERE site_name LIKE ‘[^Y]%’ 8SELECT site_name FROM site_directory WHERE site_name LIKE ‘M_crosoft’ 8SELECT site_name FROM site_directory WHERE site_desc LIKE ‘%[%]%’ 8 8SELECT site_name FROM site_directory 8SELECT site_name ‘site name’,SOUNDEX(site_name) ‘sounds like’ 9 9SELECT RTRIM(site_name) FROM site_directory 9SELECT LTRIM(RTRIM(site_name) FROM site_directory 9第二章 表的操作 10： 101）、DROP TABLE mytable 10第三章 建立索引 10 11 12 12CREATE INDEX mycolumn_index ON mytable (myclumn) 12This mand did not return data,and it did not return any rows 12DROP INDEX 12CREATE CLUSTERED INDEX mycolumn_clust_index ON mytable(mycolumn) 12WITH ALLOW_DUP_ROW 12CREATE UNIQUE COUSTERED INDEX myclumn_cindex ON mytable(mycolumn) 13CREATE INDEX name_index ON username(firstname,lastname) 13第四章 數(shù)據(jù)的插入與刪除 14 14INSERT mytable (mycolumn) VALUES (‘some data’) 14INSERT [INTO] {table_name|view_name} [(column_list)] {DEFAULT VALUES | 14INSERT mytable (first_column) VALUES(‘some value’) 14 15DELETE mytable WHERE first_column=’Deltet Me’ 15DELETE [FROM] {table_name|view_name} [WHERE clause] 15DELETE mytable WHERE first_column=’goodby’ OR second_column=’so long’ 15 15UPDATE mytable SET first_column=’Updated!’ WHERE second_column=’Update Me!’ 15{column_list|variable_list|variable_and_column_list} 15 創(chuàng)建記錄和表 16SELECT * INTO newtable FROM mytable 16SELECT first_column INTO newtable 16第一章 查詢語句、簡單的查詢： Select * from table Select * from table where column=’’ Select * from table where column like ‘%%’Select * from table where column_name between num1 and num2Select * from table where column_name not in xxSelect column_name new_name from tableSelect col_name*2 from tableSelect * from table order by col_name2 desc(注：asc是升序)Select * from table group by col_nameSelect col_name from table1,table2 from =Select distinct col_name from table 操作符和通配符Use custSelect * From students Where name Like %影%Like 操作符把記錄匹配到你說明的某個(gè)模式。這個(gè)例子是返回含“影”的任意字符串。四種通配符的含義通配符 描述% 代表零個(gè)或者多個(gè)任意字符_（下劃線） 代表一個(gè)任意字符[] 指定范圍內(nèi)的任意單個(gè)字符[^] 不在指定范圍內(nèi)的任意單個(gè)字符全部示例子如下：Like BR% 返回以BR開始的任意字符串Like br% 返回以Br開始的任意字符串Like %een 返回以een結(jié)束的任意字符串Like %en% 返回包含en的任意字符串Like _en 返回以en結(jié)束的三個(gè)字符串Like [CK]% 返回以C或者K開始的任意字符串Like [SV]ing 返回長為四個(gè)字符的字符串，結(jié)尾是ing，開始是從S到V。1
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